A DFT study on the size and defect induced properties of 2H-Au nano surface by small molecules adsorption

Abstract

The size effect and defect-related properties of the Au nanosurface in the hexagonal phase (Au2H) have been investigated by Density Functional Theory (DFT) using the adsorption of small molecules. The OH, H2O, H2O2, C2H5OH, H2 and O2 molecules were considered. The atomic H and O adsorption were also taken into account for comparison. The adsorption distances, energies, frontier molecular orbitals and density of state analysis of small molecules on top, bridge and hollow sites of the Au2H surfaces were computed in conjunction with charge distribution analysis. The size, dimension and phase-dependent adsorption energies were obtained by comparison with previous calculations. The complexes’ stability changes with the sites and interacting groups. Apart from H2O2 and C2H5OH on top site of Au2H, all studied groups’ adsorption shows exothermic character. The adsorption energies reveal the order O > OH > H > H2O> O2. The Au2H surface is most sensitive to H, O, OH and O2. Therefore, the Au2H can serve as a promising sensor to detect and recognize those atoms/molecules in practical applications. The Au2H also has potential applications as a work function-type sensor for H, OH and C2H5OH. The size limit of Au2H was defined.